Storage tank for low temperature liquids



R. S. RAE

March 15, 1960' STORAGE TANK FOR LOW TEMPERATURE LIQUIDS 2 Sheets-Sheet1 Filed Sept.

BIA/001.1 11 JAMz/L'L A345,

V NTOR. F/G. 3. E

March 15, 1960 R. S. RAE

STORAGE TANK FOR LOW TEMPERATURE LIQUIDS Filed Sept. 20, 1954 2Sheets-Sheet? /E4A/00LPH JAMl/Z EAL,

INVENTOR. 7

Y WM,

United a fis l STORAGE TANK FOR LOW TEMPERATURE LIQUIDS Randolph SamuelRae, Santa Monica, Calif., assignor to The Garrett Corporation, LosAngeles, Calif., a corporation of California I Application September 20,1954, Serial No. 457,173

4 Claims. (CI. 62-54) This invention relates to a storage tank for lowtem-' perature liquids and more particularly to tanks for storing lowtemperature liquid gases, such as liquid hydrogen, and preventing lossof the liquid by evaporation.

Low temperature liquids, such as liquid hydrogen, can be utilized asfuel for non-air breathing engines such as disclosed in pending US.application Serial No. 417,867,

filed March 22, 1954, by Randolph Samuel Rae and in order to conservethe liquid fuel it is necessary to prevent substantial evaporation. Onemethod of continually cooling the low temperature liquid is disclosed inpending US. application Serial No. 417,658, filed March 22, 1954, byRandolph Samuel Rae, now Patent No. 2,811,234, October 29, 1957, andutilizes the liquid fuel passing to the engine for cooling theevaporated gases and these cooled gases are circulated around the liquidin the tank. By the present invention, it is proposed to use a separaterefrigeration cycle in connection with the liquid storage tank so that arefrigerant of lower temperature than the liquid fuel within the tankcan be utilized to prevent excessive evaporation.

In one form of the invention, the separate refrigeration cycle utilizesa heat exchanger for reliquifying the evaporated gases and returning theliquid to the tank. The low temperature liquid passing from the tank isutilized in a second heat exchanger to cool-the refrigerant after it hasbeen compressed to a high pressure.

The refrigeration cycle can be of the usual type wherein the refrigerantis compressed, cooled and then expanded to a low temperature andpressure. In 'a second form of the invention, the refrigerant cycle alsoutilizes a heat exchanger which receives the low temperature liquidpassing from the tank in order to cool the refrigerant aftercompression. However, after the refrigerant is expanded, it is passedaround the tank in order to continually, cool the liquid within the tankand thereby prevent any substantial evaporation. The small amount ofliquid which will evaporate in the tank will be passed directly toatmosphere. Thus, both forms of the invention provide a liquid storagetank in which a low temperature liquid, such as liquid hydrogen, can bestored in ambient surroundings without excessive evaporation ofthe-liquid by utilizing a separate refrigeration cycle with arefrigerant of lower temperature than the liquification temperature ofthe liquid. When liquid hydrogen is being stored, the refrigerant'can'consist of any suitable substance, such as helium or hydrogen atlower pressure than the pressure within the tank.

It is therefore an object of the present invention to provide a storagetank for low temperature liquids which utilizes a separate refrigeartionsystem to prevent excessive evaporation of the liquid while in the tank.

tank for low temperature liquids wherein a separate refrigeration cycleis utilized to re-liquify gases evaporating from the tank.

A still further object ofthe invention is to provide.

These and other objects of the invention not specificall set forth abovewill become readily apparent from the.

following description and drawings, in which:

Figure l is a perspective view of the first form of;

the invention showing the shape of the tank.

Figure 2 is a transverse vertical section along line 2-2 of Figure 1illustrating the inlet passage and thev baffles for the tank.

;Figure 3 is a vertical section along line 3--3 of Figure 2 showing theseparate refrigeration system associated with the tank.

Figure 4 is a perspective view of a second form of the inventionillustrating the external connections to the tank. 7 1

Figure 5 is a transverse vertical section along line 5-5 of Figure 4showing the bafiles for the tank and the passages extending around thetank.

Figure 6 is a vertical section along line 6-6 of. Figure 5 showing therefrigeration system associated with;

the tank. Referring to the body having dome shaped ends. The tank has anouter skin 9 which is separated from an inner containerlfl by means ofinsulation 11. A supply tube 12, having a removable cap 13', is securedto a fitting 13 attachedto the outer skin and inner container and thepassage terminates adjacent the bottom surface of the tank. The

inner container 10 supports two vertical bafiles 14 and;

15 having openings 16 and" 17 respectively, and also.

supports a horizontal bafile 18 which has openings 19.,

The openings in both the vertical and horizontal baffles permit somemovement of the liquid within the i81'lk.' The level 20 of the liquidwithin the tank can varyv asthe liquid is withdrawn from or suppliedto'the tank. As'the liquid within the tank evaporates, a pump 21inpassage 22 draws the gases into the outer chamber 23,.

of heat exchanger 24 where the evaporated gases are again liquified andreturned to thetank through passage 25. The inner passage 26 ofheat;exchanger 24 receives the refrigerant, such as cold helium gas,from passage 27.

When liquid hydrogen is stored in the tank, the helium gas temperaturein passage 27 will be below the liquifica-Z tion temperature of thehydrogen in the tank in order to liquify the gases entering chamber 23.The refrigerant will leave the heat exchanger 24 through passage281at.

about the same temperature as the evaporated gasesin passage 22 and willenter compressor 29 whichser-ves 'to increase the pressure andtemperature of therefngeranta Compressor 29 discharges the refrigerantthrough passage 30 to the outer chamber 31' of heat exchanger 32 where,the high pressure refrigerant gas is reduced in temperature. The innerchamber 34 of heat exchanger 32 con nects with the low temperatureliquid supply in the inner container 10'thro'ugh a passage 35 whichcontains a pump. 36 for removing the liquid. Because'of the work done onthe. liquid by the pump 36, some evaporation of the lower temperatureliquid will take place prior to reach-- ing heat exchanger 32. The lowtemperature liquid will} be completely evaporated in chamberi34' andwilliex haust through passage 37 to its point of use, l such as to anon-air hr 'ng engine. The passage of the low. tem:

" perature liquid through the inner chamber 34 serves to Patented Mar-15,

first form of the invention illustrated in Figures 1 through 3, the lowtemperature liquid is; stored in a tank. 8 which is in the form of acylindrical;

lowerthe temperature of the compressed refrigerant in passage 38 leavingthe heat exchanger 32.

The high pressure, low temperature gas in passage 38 is expanded throughturbine 39 in order to substantially lower the temperature and pressureof.the refrigerant which leaves the turbine by passage 40. The passage40.' contains a cooling. coil 41 which surrounds pump 36 and serves todecrease the cavitation losses which result from gas formation at thelow pressure within the pump. The

refrigerant leaving the coil 41 is again passed to the inner chamber 26of heat exchanger 24 through passage 27.

As is diagrammatically indicated, the turbine 39 and the compressor 29can be connected together by any suitable connection so that the turbinewill drive the compressor.

Referring now to the operation of the first form of the invention, arefrigerant, such as helium gas of very low temperature, is passedthrough heat exchanger 24 in order to continually liquify the gaseswhich evaporate from the surface 20 of the low temperature liquid. Thehigher. temperature refrigerant leaving heat exchanger 24 is thencompressed by compressor 29 and these compressed, high temperature gasesare cooled in heat exchanger 32 and then expanded through turbine 39inorder to obtain lowcontinually re-liquified in heat exchanger 24 andreturned to thetank It is understood that the heat exchangers 24 and 32can take any desirable form and that the .compressor 29 can be ofthepiston or turbine type. Also, the expansion turbine 39 can be replacedby a piston type expansion engine or by a throttle valve. Of course, theinsulation 11 can be of any desired type and serves to prevent heattransfer from the tank surroundings to the low temperature liquid.

Referring to the second form of the invention illustrated in Figures 4through 6, the liquid storagetank '43 also has a cylindrical body withdome shaped ends. The tank is formed of an outer skin 44 and an innercontainer 45 which contains the low temperature liquid substance. Auniform layer of insulation 46 covers the inner container 45 and aninsulation member 47 is positioned between the outer skin and layer 46.The member 47 contains a plurality of passages 48 which pass around thetank from one end to the other and are separated by projections 49' ofthe member. A supply passage 50 is secured to afit ting 51 supported byboth the outer skin and inner container and the passage has a cap52which can be removed to supply additional low temperature liquid tothe tank.

A-pair of vertical baffles 53 and 54 .are secured to the inner container45 and contain openings 55 and 56, re-' spectviely, in order to permitsome movement of the liquid. The inner container also supports ahorizontal bafile 57 having openings 58 for permitting some movement ofthe liquid. A passage 59 connects with the upper surface of the innercontainer at a position normally above the level 60' of the lowtemperature liquid, and this passage permits the escape of evaporatedliquid to the atmosphere.

' In order to maintain the low temperature liquid at its liquificationtemperature and prevent any substantial evaporation of the liquid, apassage 60 supplies low, temperature, low pressure refrigerant to aheader space 61 which connects with all of the passages 48 extendingaround the surface of'the inner container. temperature refrigerant gaspasses from header61 around the tank through passages 48 and collects-atheader space.

62 at'the opposit end of the tank, where the'gases-are at a highertemperature because of the'heat transferred to thegasesfrom the liquidandthe' surroundings; The

This low n ma 4Q header 62 connects through passage 63 to a compressor64 which increases the pressure and temperature of the gases receivedfrom header 62 and the compressed gases from the compressor areconnected with the outer chamber 65 of heat exchanger 66 through apassage 67. The inner chamber 68 of heat exchanger 66 is connected withthe liquid in the tank through passage 69 which contains a pump 70 forwithdrawing the liquid. The low temperature liquid in passage 69'servesto cool the refrigerant gas entering theheat exchanger from passage 67and. leaves the heat exchanger as a gas through passage'71' to its pointof use, such as a non-air breathing engine. Refrigerant gas leaving heatexchanger 66 through passage 72 is expanded-man expansion turbine 73 inorder to substantially reduce the temperature and pressure of therefrigerant in'passage 74. A cooling coil 75 is connected betweenpassage 74 and passage 60 and surrounds the pump 70 in order to preventcavitation losses within the pump resulting from gas formation. As intheprevious embodiment, the compressor 64 and turbine 73 are connectedtogether by a suitable shaft connection 76 so that the turbine willdrive the compressor.

In operation, the refrigerant system takes the low temperature gas, suchas helium, and compresses it to high temperature and pressureincompressor 64. This gas is then cooledto a low temperature by heatexchangor 66 and is then expanded to a low pressure and lowertemperature through expansion turbine 73. The ex panded gas is thenpassed around the pump 70 and perature liquid is available for itsintended use. As in the previous-embodiment, the compressor 64 can be.either of the piston or turbine type-and theexpansiou turbine 73 can bereplaced by either a piston expansion engine or a throttle valve.

By the present invention, a storage tank for low temperature liquids hasbeen provided which prevents the loss of any substant-ial portion of theliquid through evaporation. It is understood that any refrigerant can beused in the refrigeration cycle andthat the refrigerant mustbe of alower temperature than the storedlow temperature liquid. When liquidhydrogen is stored helium gas can be used as the refrigerant since ithas a liquificationtemperature lower than that of hydrogen and other lowtemperature refrigerants could be used, including.

hydrogen at a lower pressure than the pressure of the liquid hydrogenwithin the tank.

evaporation of-the liquid by preventing heat transfer from thesurrounding-atmosphere.

around the inner container of the second form andthat various types ofinsulation material could be used in both forms of the invention.- Theouter skin and inner containerfor both tanks can be formed of anysuitable material. such as steel or plastic, which will withstand thelow temperatures. Various other modifications are con templated by thoseskilled in the art without departing from the spirit and scope of theinvention as hereinafter defined by the appended claims.

What is claimed is:

1. An apparatus for storing gas material in theform of low'temperatureliquid comprising a storage tankfor said liquid, passage meanssurrounding the liquid with-inf the tank for cooling the liquid, andmeans for-supplying refrigerant to said passage means 'at a lower temr.peraturethan-said' liquid, said supplying means comprising means forcompressing said refrigerant to high pres:

7 sure and means for expanding the compressed refrigerant It isunderstood thatv the insulationmembers 11, 46 and 47 aid in preventing-It is also contem platedthat various types of passage means could extendto low pressure and temperature, heat exchanger means positioned betweensaid compressor means and said expansion means to reduce the temperatureof said refrigerant after compression, conduit means for connecting saidlow temperature liquid in the tank with said heat exchanger means, pumpmeans positioned insaid conduit means for circulating liquid from saidtank through said heat exchange means, and coil means surrounding saidpump meansand connected with said expansion means to continually coolsaid pump means and prevent cavitation losses.

2. An apparatus for storing gas material in the form of low temperatureliquid comprising a storage tank for said liquid, passage means locatedadjacent said tank and in heat exchange relationship with the gasevaporating from the liquid, and means for supplying said passage meanswith a refrigerant of lower temperature than said liquid in order tocontinually cool said evaporated gas, said supplying means comprisingcompressor means and expansion means for said refrigerant, heatexchanger means connected with said compressor means and said expansionmeans for cooling the compressed refrigerant prior to entering saidexpansion means, conduit means for connecting said heat exchanger meanswith the low temperature liquid in said tank, pump means in said conduitmeans for circulating low temperature liquid from shell, insulationmeans positioned between said inner container and said shell, passagemeans for a refrigerant formed in said insulation means and completelysurrounding the surface of said inner containerto cool all the liquid,header means at each end of said tank connecting with said passagemeans, compressor means I connected with one of said header means forcompressing saidrefn'gerant to high temperature and pressure, ex-

pansion means connected with said compressor means for liquid from saidtank to said heat exchanger means in order'to reduce the temperature ofsaid compressed refrigerant, pump means for said supply means, and acoil in said connecting means and surrounding said pump means in orderto prevent cavitation losses resulting from the evaporation of saidliquid within said pump means.

4. An apparatus as defined in claim 3 having a passage connecting theupper space of said tank to atmosphere to vent any gas evaporating fromsaid liquid.

References Cited in the file of this patent UNITED STATES PATENTS646,459 Place Apr. 3, 1900 1,088,052 Aumont Feb. 24, 1914 1,440,000Bonine Dec. 26, 1922 2,379,215 Brinkmann June 26, 1945 2,480,093Anderson Aug. 23, 1949 2,617,264 McGovern et a1. Nov. 11, 1952 2,682,154Wilkinson June 29, 1954

